U.S. patent number 6,818,026 [Application Number 09/783,031] was granted by the patent office on 2004-11-16 for process for producing fatty acid esters and fuels comprising fatty acid ester.
This patent grant is currently assigned to Sumitomo Chemical Company, Limited. Invention is credited to Toshio Sasaki, Tatsuo Tateno.
United States Patent |
6,818,026 |
Tateno , et al. |
November 16, 2004 |
Process for producing fatty acid esters and fuels comprising fatty
acid ester
Abstract
A process for producing a fatty acid ester with a high yield
from an oil or fat and an alcohol which comprises reacting an oil
or fat with an alcohol in the presence of a solid base catalyst
under conditions in which at least one of the oil or fat and the
alcohol is in a supercritical state at a temperature exceeding
260.degree. C.
Inventors: |
Tateno; Tatsuo (Niihama,
JP), Sasaki; Toshio (Ichihara, JP) |
Assignee: |
Sumitomo Chemical Company,
Limited (Osaka, JP)
|
Family
ID: |
26585538 |
Appl.
No.: |
09/783,031 |
Filed: |
February 15, 2001 |
Foreign Application Priority Data
|
|
|
|
|
Feb 17, 2000 [JP] |
|
|
2000-039316 |
Feb 17, 2000 [JP] |
|
|
2000-039318 |
|
Current U.S.
Class: |
44/385; 508/463;
554/167; 554/174 |
Current CPC
Class: |
C07C
67/03 (20130101); C10L 10/04 (20130101); C10M
105/34 (20130101); B01J 3/008 (20130101); C10L
1/19 (20130101); C10L 1/026 (20130101); B01J
23/755 (20130101); C11C 3/003 (20130101); C10L
1/1817 (20130101); C07C 67/03 (20130101); C07C
69/52 (20130101); C10M 2207/282 (20130101); B01J
2219/00099 (20130101); C10M 2207/286 (20130101); C10M
2207/281 (20130101); Y02P 20/544 (20151101); C10M
2207/283 (20130101); Y02E 50/13 (20130101); Y02E
50/10 (20130101); Y02P 20/54 (20151101); B01J
2219/00058 (20130101) |
Current International
Class: |
B01J
3/00 (20060101); C10L 1/18 (20060101); C07C
67/00 (20060101); C10L 1/10 (20060101); C10M
105/00 (20060101); C10M 105/34 (20060101); B01J
23/755 (20060101); C11C 3/00 (20060101); C07C
67/03 (20060101); C10L 1/19 (20060101); C10L
10/00 (20060101); C10L 1/02 (20060101); C10L
1/00 (20060101); C10L 10/04 (20060101); C10L
001/18 () |
Field of
Search: |
;44/385 ;554/167,174
;508/463 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
2124166 |
|
Jan 1999 |
|
ES |
|
795573 |
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May 1958 |
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GB |
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61254255 |
|
Nov 1986 |
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JP |
|
7197047 |
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Aug 1995 |
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JP |
|
9235573 |
|
Sep 1997 |
|
JP |
|
200044984 |
|
Feb 2000 |
|
JP |
|
WO 9601304 |
|
Jan 1996 |
|
WO |
|
WO 0005327 |
|
Feb 2000 |
|
WO |
|
WO0005327 |
|
Feb 2000 |
|
WO |
|
Other References
Ullmann's Enclyclopedia of Industrial Chemistry, Fifth Completely
Revised Edition, vol. A10 (1987), p. 281. .
Ullmann's Encyclopedia of Industrial Chemistry, Fifth Completely
Revised Edition, vol. 11 (1976), p. 432. .
Udo R. Kreutzer, Journal of the American Oil Chemists' Society,
vol. 61, No. 2. .
G.R. Peterson et al.; Journal of the American Oil Chemists'
Society, vol. 61, No. 10, 1984, pp. 1593-1597. .
Shiro Saka et al.; Biomass, Proc. Biomass Conf. Am., vol. 1, 1999,
pp. 797-801..
|
Primary Examiner: Toomer; Cephia D.
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Claims
What is claimed is:
1. A process for producing a fatty acid ester from an oil or fat
and an alcohol, wherein the process comprises reacting an oil or
fat with an alcohol in the presence of a solid base catalyst
comprising at least one component selected from the group
consisting of sodium carbonate, calcium oxide, calcium hydroxide,
calcium carbonate and magnesium oxide under conditions in which at
least one of the oil or fat in an amount of 0.001 parts by weight
or more based on 100 parts by weight of the oil or fat and the
alcohol is in a supercritical state at a temperature of 270.degree.
C. or more, said solid base catalyst being present in an amount of
3 to 6 parts by weight based on 100 parts by weight of the oil or
fat.
2. A process for producing a fatty acid ester from an oil or fat
and an alcohol, wherein the process comprises reacting an oil or
fat with an alcohol in the presence of a nickel-containing solid
catalyst under conditions in which at least one of the oil or fat
and the alcohol is in a supercritical state.
3. The process according to claim 2, wherein the nickel-containing
solid catalyst is a catalyst containing an oxide of nickel.
4. The process according to claim 1 or 2, wherein the alcohol is in
a supercritical state.
5. The process according to claim 4, wherein the alcohol is
represented by the following formula (1):
wherein R is a hydrocarbyl group having 1 to 10 carbon atoms, or a
hydrocarbyl group substituted by a hydrocarbyloxyl group which
substituted hydrocarbyl group has 2 to 10 carbon atoms.
6. The process according to claim 5, wherein R in the formula (1)
is an alkyl group having 1 to 4 carbon atoms.
7. The process according to claim 5, wherein R in the formula (1)
is methyl group or ethyl group.
8. The process according to claim 5, wherein R in the formula (1)
is methyl group.
9. The process according to claim 1 or 2, wherein the oil or fat is
a waste oil or fat.
10. The process according to claim 1 or 2, wherein the oil or fat
is a waste edible oil.
11. The process according to claim 1, wherein the alcohol is in a
supercritical state at a temperature within the range of from 270
to 400.degree. C.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing a fatty
acid ester and glycerol by reacting an oil or fat with an alcohol,
and to a fuel comprising a fatty acid ester obtained by the above
process.
2. Description of Related Art
A principal component of the oil or fat is esters composed of a
fatty acid and glycerol, called triglycerides. Fatty acid esters
obtained by transesterification of an oil or fat with an alcohol
have found wide applications as industrial raw materials,
pharmaceuticals and so on.
Processes have been described for manufacturing fuels for diesel
engine or base oils for lubricant oil containing fatty acid esters
as substitutes for the conventional mineral oils, by
transesterification of an oil or fat with an alcohol. For example,
in JP-A-9-235573 and JP-A-7-197047, a fuel for diesel engine is
produced by reacting a waste edible oil and methanol in the
presence of sodium hydroxide. In JP-A-7-197047, transesterification
is usually carried out with an alkali catalyst such as sodium
hydroxide under the atmospheric pressure at a temperature of 50 to
70.degree. C. In this case, a pre-treatment is essential because,
when a free fatty acid exists in an oil or fat as a raw material,
it reacts with the alkali catalyst to form a soap. In addition, a
after-treatment for separation is also required because a small
amount of a soap is produced in the course of the
transesterification even when the pre-treatment is carried out.
On the other hand, it has been known that, when the
transesterification is carried out under conditions of 9 to 10 MPa
and 220 to 250.degree. C., an oil or fat of a low purity containing
free fatty acids can be used as a raw material [Ullmann's
Encyclopedia of Industrial Chemistry, Fifth Completely Revised
Edition, Vol. A10 (1987), p. 281].
In addition, in U.S. Pat. No. 5,713,965, a technology is disclosed
in which a fuel for diesel engine and a lubricant oil containing
fatty acid esters are produced from an oil or fat and an alcohol in
the presence of a lipase in a hexane solvent. An example has also
been known in which a fatty acid ester is produced from an oil or
fat and an alcohol with addition of a catalyst under pressure
[Ullmann Enzyclopaedie der Technischen Chemie, Vielte Edition, Vol.
11 (1976), p. 432]. That is, the reaction is carried out with an
alkali catalyst or a zinc catalyst under conditions of 10 MPa,
240.degree. C. and 7 to 8 times excess of methanol.
A technology has also been known in which fatty acid esters are
produced by continuously reacting an oil or fat with an alcohol at
240.degree. C. and 9 MPa (90 bar) in the presence of an alkali
catalyst [Journal of the American Oil Chemists' Society, Vol. 61,
No. 2(1984)]. Detail of the alkali catalyst, however, is
unclear.
Furthermore, a process has been proposed in which the reaction is
carried out using sodium carbonate or sodium hydrogen carbonate as
a heterogeneous solid catalyst under conditions including the
ordinary pressure or a pressure approximately the ordinary pressure
at a boiling point of the used alcohol or a temperature
approximately such point (JP-A-61-254255). The reaction in this
process, however, is slow and thus the productivity is
insufficient.
A technology has also been known in which fatty acid esters are
produced by reacting an oil or fat with an alcohol within a range
of 170 to 250.degree. C. at 10 MPa (100 bar) or below in the
presence of a catalyst of ZnO or a complex oxide of Zn and Al (U.S.
Pat. No. 5,908,946), but the reaction is also slow.
Moreover, a process has been proposed in which a monoglyceride is
selectively produced by reacting an oil or fat with an alcohol
within a range of 25 to 260.degree. C. at a pressure of 0.1 MPa (1
atm) to 10.1 MPa (100 atm) using a solid catalyst containing an
alkaline earth metal oxide or the like, but there is no disclosure
for a process for producing fatty acid alkyl esters and
glycerol.
An object of the present invention is to provide a process for
producing a fatty acid ester and glycerol from an oil or fat with
an alcohol under more adequate conditions and efficiently and with
a high yield, as well as a fuel and others containing the fatty
acid ester.
SUMMARY OF THE INVENTION
As the result of extensive studies on a process for producing a
fatty acid ester and glycerol by reacting an oil or fat with an
alcohol and on a fuel containing said fatty acid ester, the present
inventors have found the fact that the reaction proceeds with a
high yield when the reaction is carried out with addition of a
solid base catalyst and under conditions in which the oil or fat
and/or the alcohol are/is in a supercritical state exceeding
260.degree. C., or when the reaction is carried out with addition
of a nickel-containing solid catalyst and under conditions in which
the oil or fat and/or the alcohol are/is in a supercritical state,
and thus have completed the invention. Therefore, the present
invention includes the following features:
[1] A process for producing a fatty acid ester from an oil or fat
and an alcohol, wherein the process comprises reacting an oil or
fat with an alcohol in the presence of a solid base catalyst under
conditions in which at least one of the oil or fat and the alcohol
is in a supercritical state at a temperature exceeding 260.degree.
C.
[2] A process for producing a fatty acid ester from an oil or fat
and an alcohol, wherein the process comprises reacting an oil or
fat with an alcohol in the presence of a nickel-containing solid
catalyst under conditions in which at least one of the oil or fat
and the alcohol is in a supercritical state.
[3] A fuel comprising a fatty acid ester obtained by the process
according to the above described [1] or [2].
[4] A fuel for diesel engine comprising a fatty acid ester obtained
by the process according to the above described [1] or [2].
[5] A base oil for lubricant oil comprising a fatty acid ester
obtained by the process according to the above described [1] or
[2].
[6] A fuel oil additive comprising a fatty acid ester obtained by
the process according to the above described [1] or [2].
DETAILED DESCRIPTION OF THE INVENTION
The reaction in the invention is described below in detail.
A principal reaction in the process of the invention is represented
by the following reaction scheme (2): ##STR1##
wherein R.sub.1, R.sub.2 and R.sub.3, independent with each other,
represent carbon chains of fatty acids, with carbon numbers in
R.sub.1, R.sub.2 and R.sub.3 depending on kind of the oil or fat,
and R.sub.4 represents a hydrocarbyl group which may be substituted
with a hydrocarbyloxy group.
The oil or fat used in the present invention contains a
triglyceride, an ester of a fatty acid and glycerol, as a principal
component. The expression "contains a triglyceride as a principal
component" refers to the fact that it contains a triglyceride in an
amount of 50% by weight or more of the oil or fat.
The oil or fat used in the present invention is a material
containing a triglyceride of a fatty acid shown in the reaction
scheme (2) and may be a natural oil or fat or a synthetic oil or
fat.
Typical examples of oil or fat include, without limitation, lard
tallow, chicken tallow, butter fat, beef tallow, cocoa butter fat,
corn oil, peanut oil, cotton seed oil, soybean oil, rapeseed oil,
coconut butter, olive oil, safflower oil, coconut oil, oak oil,
almond oil, apricot kernel oil, beef bone fat, walnut oil, castor
oil, chaulmoogra oil, Chinese vegetable tallow, cod liver oil,
cotton seed stearin, sesame oil, deer tallow, dolphin tallow,
sardine oil, mackerel oil, horse fat, pork tallow, bone oil,
linseed oil, mutton tallow, neat 's foot oil, palm oil, palm kernel
oil, porpoise oil, shark oil, sperm whale oil, tung oil, whale oil
and so on. In addition, the oil or fat may be a mixture of
plurality of these oils or fats, an oil or fat containing a
diglyceride or a monoglyceride, or a partly denatured oil or fat
such as oxidized, reduced or others. Furthermore, it may be an
unpurified oil or fat containing a free fatty acid, water or other,
or waste oil or fat discarded by restaurant, food industries or
common homes. It is preferred that an appropriate pre-treatment is
applied as required.
For example, when the present invention is applied to a waste oil
such as waste edible oil, it is preferred to remove insoluble
solids from the oil or fat by a mesh, filter or the like before It
is fed to a preheating machine, because sometimes steady operation
is inhibited due to occlusion of a pressure pump or a
pressure-adjusting valve by an insoluble solid if contained in the
oil or fat.
The oil or fat may contain any other component than oil or fat
itself. Specific examples include, without limitation, crude oil,
heavy oil, light oil, mineral oil, essential oil, coal, fatty
acids, saccharides, metal powders, metal salts, proteins, amino
acids, hydrocarbons, cholesterol, flavors, pigment compounds,
enzymes, perfumes, alcohols, fibers, resins, rubbers, paints,
cements, detergents, aromatic compounds, aliphatic compounds, soot,
glass, earth and sand, nitrogen-containing compounds,
sulfur-containing compounds, phosphor-containing compounds,
halogen-containing compounds and the like.
When the above-described substances contained in the oil or fat
have a possibility of participating in the reaction, for example,
have a possibility of inhibiting the reaction, or they are solid
and have a possibility of occluding in the process of production or
other similar possibility, it is preferred to remove them by a
treatment such as filtration, distillation or the like before the
reaction.
The method for distillation include, without limitation,
distillation under reduced pressure, steam distillation, molecular
distillation, extractive distillation and the like.
In the present invention, waste oils or fats and waste edible oils
or fats can also be used as the oil or fat.
The alcohol (compound 2 in the reaction scheme (2)) used in the
present invention is not particularly limited and preferably an
alcohol represented by the general formula:
wherein R represents a hydrocarbyl group having 1 to 10 carbon
atoms or a hydrocarbyl group having 2 to 10 carbon atoms in total
substituted with a hydrocarbyloxy group.
The hydrocarbyl group having 1 to 10 carbon atoms as R includes,
for example, alkyl group, aralkyl group, alkenyl group, alkynyl
group and the like.
Examples of the alcohol having an alkyl group as R include
methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol,
t-butanol, pentanol, hexanol, cyclohexanol, heptanol and the
like.
Examples of the alcohol having an aralkyl group as R include benzyl
alcohol, a-phenethyl alcohol, a-phenethyl alcohol and the like,
with benzyl alcohol being preferred.
Examples of the alcohol having an alkenyl group as R include allyl
alcohol, 1-methyl-allyl alcohol, 2-methyl-allyl alcohol,
3-butene-1-ol, 3-butene-2-ol and the like, with allyl alcohol being
preferred.
Examples of the alcohol having an alkynyl group as R include
2-propyne-l-ol, 2-butyne-1-ol, 3-butyne-l-ol, 3-butyne-2-ol and the
like.
Examples of the alcohol having a hydrocarbyl group having 2 to 10
carbon atoms in total substituted with a hydrocarbyloxy group
include 2-methoxyethanol, 2-methoxypropanol, 3-methoxybutanol and
the like.
Among them, preferred alcohol has an alkyl group having 1 to 4
carbon atoms as R. Specifically, the alcohol is preferably methanol
wherein R is a methyl group, ethanol wherein R is an ethyl group,
propanol wherein R is a propyl group, isopropanol wherein R is an
isopropyl group, n-butanol wherein R is a n-butyl group, isobutanol
wherein R is an isobutyl group, t-butanol wherein R is a t-butyl
group, more preferably methanol or ethanol and most preferably
methanol. Purity of the alcohol is not particularly limited and it
is preferably 95% or above, more preferably 98% or above. The
alcohol may be used independently or in admixture of two or
more.
When the alcohol may exist in optical isomer forms, such optical
isomers are intended to be included.
It is preferred that the alcohol is fed in a weight 1 to 100 times
the theoretical feeding weight calculated according to the
following formula:
wherein saponification value of oil or fat refers to an amount,
represented by mg, of potassium hydroxide required for complete
saponification of 1 g of the oil or fat.
The number of times less than 1 is not preferred because the
reaction yield decreases. The number of times more than 100 is not
preferred because the apparatus may become too large.
Representative fatty acid ester 3 producible by the reaction in the
scheme (2) includes, without limitation, esters of valeric acid,
caproic acid, enanthoic acid, caprylic acid, pelargonic acid,
capric acid, undecylic acid, lauric acid, tridecylic acid, myristic
acid, pentadecylic acid, palmitic acid, heptedecylic acid, stearic
acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric
acid, cerotic acid, heptacosanoic acid, montanic acid, melissic
acid, lacceric acid, crotonic acid, isocrotonic acid, undecylenic
acid, oleic acid, elaidic acid, cetoleic acid, erucic acid,
brassidic acid, sorbic acid, linoleic acid, linolenic acid,
arachidonic acid, propiolic acid, stearolic acid, nervonic acid,
ricinoleic acid, (+)-hydnocarpic acid, (+)-chaulmoogric acid and
the like. Alcoholic residue of esters depends on the alcohol used.
For, example, a methyl ester is obtained when methanol is used as
the alcohol, and an ethyl ester is obtained when ethanol is used as
the alcohol.
Furthermore, when optical isomers exist in the fatty acid moiety,
such optical isomers are also encompassed in the present
invention.
In addition, in the process of the present invention, glycerol 4 is
produced as a principal product other than the fatty acid
ester.
Next, the catalyst used in the present invention is described.
The solid base catalyst used in the present invention is the solid
having surface basicity such as a metal oxide, metal salt,
supported base, complex oxide, zeolite or the like, described in
Shokubai Koza, Vol. 10, Shokubai Kakuron, Ed. Shokubai Gakkai,
Published by Kodansha, 1986, page 51 [Lectures on Catalysts. Vol.
10, Individual Catalysts, Ed. Catalyst Society of Japan, Published
by Kodansha, 1986, page 51]. Among them, preferred catalyst is a
catalyst containing at least one of sodium carbonate, calcium
oxide, calcium hydroxide, calcium carbonate and magnesium
oxide.
The amount of the catalyst to be used is preferably 0.001 part by
weight to 6 parts by weight, more preferably 0.005 part by weight
to 3 parts by weight, based on 100 parts by weight of the oil or
fat.
The solid catalyst containing a nickel compound used in the present
invention includes, for example, solid catalysts containing nickel
oxides (NiO, Ni.sub.2 O.sub.3, complex oxides of NiO and Ni.sub.2
O.sub.3), nickel carbonate, nickel hydroxide, basic nickel
carbonate and the like, and further, solid catalysts on a support
such as silica gel, zeolite or the like treated for impregnation of
a nickel compound and others. Preferred catalysts are catalysts
containing an oxide of nickel.
The amount of the catalyst containing a nickel compound to be used
is preferably 0.01 part by weight to 6 parts by weight, more
preferably 0.1 part by weight to 3 parts by weight, based on 100
parts by weight of the oil or fat.
The supercritical state referred to in the present invention means
the following state.
Substances may exist in one of three intrinsic states, gas, liquid
and solid, and in addition, may exist in fluid phase which does not
condense under pressure when they are at a temperature above the
critical temperature. This last state is referred to as the
supercritical state.
Fluids in the supercritical state show a behavior different from
the normal states of liquid or gas. The fluids in the supercritical
state is a "non-liquid solvent" having a density approximate to
that of liquid, a viscosity approximate to that of gas, and a
thermal conductivity and a diffusion coefficient which are
intervenient between those of gas and of liquid. Its low viscosity
and high diffusion favor mass transfer therein, and its high
thermal conductivity enables high thermal transmission. Because of
such a special state, the reactivity in the supercritical state is
higher than that in the normal gaseous or liquid state and thus the
transesterification is promoted.
When a nickel-containing solid catalyst is used in the present
invention, it is preferred to carry out the reaction under
conditions in which the oil or fat and/or the alcohol are/is in a
supercritical state. Such conditions include the conditions (a) to
(c) indicated below:
(a) Conditions under which the mixture of the oil or fat and the
alcohol is in a supercritical state.
(b) Conditions under which the alcohol is in a supercritical
state.
(c) Conditions under which the oil or fat is in a supercritical
state.
Among them, the conditions (a) or (b) are preferred for carrying
out the reaction.
Specifically, for the condition (b) using methanol as the alcohol,
the reaction is carried out at a temperature of 240.degree. C. or
more because the critical temperature of methanol is 240.degree. C.
When ethanol is used, the reaction is carried out at a temperature
of 243.degree. C. or more because the critical temperature of
ethanol is 243.degree. C. In the case of propanol, the reaction is
carried out at a temperature of 264.degree. C. or more because the
critical temperature of propanol is 264.degree. C. When butanol is
used, the reaction is carried out at a temperature of 287.degree.
C. or more because the critical temperature of butanol is
287.degree. C. When isopropanol is used, the reaction is carried
out at a temperature of 236.degree. C. or more because the critical
temperature of isopropanol is 236.degree. C. When isobutanol is
used, the reaction is carried out at a temperature of 275.degree.
C. or more because the critical temperature of isobutanol is
275.degree. C. When t-butanol is used, the reaction is carried out
at a temperature of 233.degree. C. or more because the critical
temperature of t-butanol is 233.degree. C.
When the solid base catalyst is used in the invention, the
temperature at which an oil or fat is reacted with an alcohol is
preferably within a range of a temperature exceeding 260.degree. C.
up to 420.degree. C. When the reaction temperature is 260.degree.
C. or below, the reaction velocity is slow. A temperature exceeding
420.degree. C. is not preferred because decomposition reaction or
others may occur. More preferred range of temperature is a
temperature exceeding 260.degree. C. to 400.degree. C., further
preferred range of temperature is a temperature from271.degree. C.
or more to 400.degree. C., further more preferred range of
temperature is a temperature from 280.degree. C. or more to
400.degree. C.
When a nickel-containing solid catalyst is used in the invention,
the temperature at which an oil or fat is reacted with an alcohol
is within a range of a temperature at which the oil or fat and/or
the alcohol are/is in a supercritical state. The upper limit of the
reaction temperature is not critical but preferably 400.degree. C.
or below, because of possible decomposition reaction.
The density condition of the alcohol in a reaction vessel in which
the oil or fat is reacted with the alcohol according to the present
invention is preferably within a range of 0.01 g/cm.sup.3 to 0.4
g/cm.sup.3, and the pressure condition is preferably within a range
of 0.5 MPa to 25 MPa.
The time period for reacting an oil or fat with an alcohol
according to the present invention is preferably within a range of
0.1 minute to 180 minutes, more preferably within a range of 0.5
minute to 120 minutes, and further, most preferably within a range
of 1 minute to 60 minutes.
The reaction can be carried out in various reaction modes. For
example, the reaction may be carried out either in batch system or
in flow system.
In addition, in the invention, the oil or fat and the alcohol may
either be homogeneously mixed throughout the reaction or be
separated into two phases insofar as the reaction can occur.
When they are separated into two phases, the reaction can be
promoted more effectively by enlarging the contact surface between
the two phases, for example, through agitation of the reaction
system.
The reaction mixture after the reaction contains a fatty acid
ester, glycerol and an excess unreacted alcohol, and in addition,
may contain unreacted raw materials and other impurities.
The fatty acid ester is purified from the reaction mixture to a
purity required for the individual application. Methods for
purification are not particularly limited and general methods such
as distillation, extraction and the like can be applied depending
on the property of the fatty acid ester to be produced.
When a case wherein methanol is used as the alcohol is taken as an
example, the mixture is stood for separation of light liquid and
heavy liquid after recovering an excess (or unreacted)methanol
component by evaporation. Separation of the solid base catalyst and
the nickel-containing solid catalyst used in the present invention
from a reaction solution is rather easy and thus after-treatment of
the reaction solution is rather simple an compared with the case of
sodium hydroxide or the like. The light liquid contains fatty acid
methyl ester as a principal component and can be utilized as a raw
material for fuel for diesel engines or a raw material for natural
higher alcohol. The heavy liquid containing glycerol as a principal
component can be utilized as a raw material for industrial
glycerol.
Representative means for separation of unreacted alcohol includes,
without limitation, mixer-settler extraction, liquid-liquid
extraction, extraction with a pulse column, jet extraction,
Podbielniak rotary extraction and the like, in addition to
distillation such as distillation under reduced pressure. The fatty
acid ester maybe taken out after completely separating the alcohol
or may be recovered in a state containing a residual alcohol.
Depending on structure of the oil or fat as the raw material, the
fatty acid ester produced according to the present invention is
generally in the form of a mixture of several fatty acid esters
when a natural oil or fat is used. In this case, depending on the
application, either the mixture itself can be used or a specific
fatty acid ester can be used after isolating it by a common method
such as distillation, extraction or the like, as required.
The fatty acid ester produced by the above-described manner can be
used in fuels such as a fuel for diesel engine, a base oil for
lubricant oil, an additive for fuel oil and the like by itself or
in admixture with other components according to the requirements
derived from the use.
As described in SHINPEN JIDOUSHA KOGAKU HANNDOBUKKU (Ed.
SHADANNHOUJINN JIDOUSHAGIJUTSUKAI) [A New Handbook of Automobile
Engineering (Ed. Corporation of Automobile Technology)],
ignitability and viscosity are important items in the case of use
in the fuel for diesel engine. Because use of a fatty acid ester
having a relatively low viscosity may be a cause for abrasion or
seizing, it is essential to use a fatty acid ester having a
viscosity adapted to diesel engine. In addition, because a fatty
acid ester with too high molecular weight may be a cause for odor
or smoke, such ester is not preferred.
Examples of preferably used esters for use in fuel for diesel
engine include fatty acid methyl ester, fatty acid ethyl ester,
fatty acid isopropyl ester, fatty acid isobutyl ester and the like.
Among them,fatty acid isopropyl ester and fatty acid isobutyl ester
produce a fuel for diesel engine having a high performance at a low
temperature.
The viscosity is also an important item in the Case of use in base
oil for lubricant oil. While it is desirable that the ester for
summer season has a relatively high viscosity in order to obtain a
high lubricity, a fatty acid ester with relatively low viscosity
and high flowability is desirable when it is used in the winter
season or in a place of low temperature. Therefore, a wide variety
of fatty acid esters can be used as a base oil for lubricant
oil.
In the case of the additive for fuel oil, the fatty acid ester is
added to a fuel mainly for decreasing friction. The ester has a
role similar to that in the lubricant oil and similar properties to
those in the base oil for lubricant oil are preferred.
Depending on use, the fatty acid esters as produced may contain
glycerol , excess unreacted alcohol, unreacted oil or fat and other
impurities, in a reaction mixture after reaction is completed, if
they have no problem in use.
In addition, the yield can be increased by repeating the reaction
under conditions provided in the present invention or other means,
when required by desired use.
According to the present invention, a process for producing a fatty
acid ester from an oil or fat and an alcohol by a simple convenient
process and with a high yield, as well as a fuel and others
containing a fatty acid ester, can be provided. Therefore, the
invention has a great industrial value. In addition, the invention
is useful from the viewpoint of reuse of resources and prevention
of public pollution.
EXAMPLES
The present invention will now be described in more detail with
reference to Examples, which should not be construed as a
limitation upon the scope of the invention.
Example 1
After weighing 0.860 g of soybean oil as the oil or fat containing
triglycerides as principal components, 1.240 g of methanol as the
alcohol, and 5.8 mg of powdery anhydrous sodium carbonate as the
catalyst, they were charged in a stainless steel reaction tube
(about 4.5 cm.sup.3), which was then sealed. The reaction tube was
placed in a fluidized bed sand bath controlled at a temperature of
300.degree. C. and the reactants were heated and reacted. After 10
minutes, the tube was taken out (placed for 10 minutes in the sand
bath) and immediately placed in water for cooling.
The amount of methanol used in this reaction was about 13 times the
theoretical amount necessary for complete methyl-esterification of
the soybean oil. The temperature at a wall of the reaction tube was
measured by attaching thermocouple. The wall exceeded about
260.degree. C. after 2 minutes and was about 300.degree. C. after
10 minutes. The density of methanol at the initial state of the
reaction was 0.28 g/cm.sup.3, as calculated from a reaction
volume.
Then, the reaction solution in the reaction tube was subjected to
the first recovery and repeatedly washed three times with methanol.
The used catalyst was separated by precipitation in the recovered
solution. The reactivity was evaluated by quantitatively analyzing
the methyl ester component and the glycerol component in the
recovered solution using gas chromatography (GC). It was found that
the yield of the fatty acid methyl ester was about 99% and that of
glycerol was about 99% (as shown in Table 1). The yields here were
values calculated on the basis of a reaction in which 3 moles of
fatty acid methyl easters and 1 mole of glycerol were formed from 1
mole of soybean oil.
The components in the reaction solution were analyzed by size
exclusion chromatography (SEC) in which compounds were separated
according to differences in molecular weight. The results are also
shown in Table 1.
Examples 2, 3 and 4
Tests in Example 1 were substantially repeated except that calcium
oxide, calcium hydroxide and magnesium oxide, respectively, were
used as the catalyst. The results of analysis by GC and SEC on the
recovered solutions are shown in Table 1.
Example 5
Tests in Example 1 were substantially repeated except that the
temperature in the fluidized bed sand bath was controlled to
350.degree. C. and the reaction tube was placed for 4 minutes. The
temperature at the wall of the reaction tube exceeded 260.degree.
C. after about 1.3 minute and was about 340.degree. C. after 4
minutes. The results of analysis by GC and SEC on the recovered
reaction solution are shown in Table 1.
Examples 6, 7 and 8
Tests in Example 1 were substantially repeated except that calcium
hydroxide, calcium oxide and calcium carbonate, respectively, were
used as the catalyst and soybean oil in which 0.01% of powders of
catalysts were previously added and dispersed was used. The results
of analysis by GC and SEC on the recovered reaction solutions are
shown in Table 1.
Example 9
Tests in Example 1 were substantially repeated except that 0.744 g
of a soybean oil as the oil or fat in which 0.01% of powders of
sodium calcium catalyst was previously added and dispersed and
1.084 g of methanol as the alcohol were used, the temperature in
the sand bath was controlled to 400.degree. C. and the reaction
tube was placed for 2 minutes. The temperature at the wall of the
reaction tube in this test exceeded about 260.degree. C. after 0.6
minute and was about 360.degree. C. after 2 minutes.
The results of analysis by SEC on the recovered reaction solution
are shown in Table 1.
Comparative Example 1
Tests in Example 1 were substantially repeated except that the
temperature in the fluidized bed sand bath was controlled to
250.degree. C. and the reaction tube was placed for 10 minutes. The
temperature at the wall of the reaction tube was about 230.degree.
C. after 2 minutes and was about 250.degree. C. after 10 minutes.
The results of analysis by GC and SEC on the recovered reaction
solution are shown in Table 1.
Example 10
After weighing 0.861 g of soybean oil as the oil or fat containing
triglycerides as principal components, 1.242 g of methanol as the
alcohol, and 10.9 mg of powdery nickel oxide (complex oxide of NiO
and Ni.sub.2 O.sub.3) as the catalyst, they were charged in a
stainless steel reaction tube (about 4.5 cm.sup.3), which was then
sealed. The reaction tube was placed in a fluidized bed sand bath
controlled at a temperature of 300.degree. C. and the reactants
were heated and reacted, After 10 minutes, the tube was taken out
and immediately placed in water for cooling. The amount of methanol
used in this reaction was about 13 times the theoretical amount
necessary for complete methyl-esterification of the soybean oil.
The temperature at a wall of the reaction tube was measured by
attaching thermocouple. The wall exceeded about 260.degree. C.
after 2 minutes indicating that the temperature exceeded the
critical temperature of methanol. The density of methanol at the
initial state of the reaction was 0.28 g/cm.sup.3, as calculated
from a reaction volume.
Then, the reaction solution in the reaction tube was subjected to
the first recovery and repeatedly washed three times with methanol.
The used catalyst was separated by precipitation in the recovered
solution. The reactivity was evaluated by quantitatively analyzing
the methyl ester component and the glycerol component in the
recovered solution using gas chromatography. It was found that the
yield of the methyl ester was about 98% and that of glycerol was
about 91%. The yields here were values calculated on the basis of a
reaction in which 3 moles of fatty acid methyl esters and 1 mole of
glycerol were formed from 1 mole of soybean oil.
Example 11
Tests in Example 10 were substantially repeated except that 0.867 g
of a soybean oil, 1.241 g of methanol and 29.1 mg of the powdery
nickel oxide were used. The results of analysis made on the
recovered reaction solution showed that the yield of the methyl
ester was about 98% and that of glycerol was about 91%.
Comparative Example 2
Tests in Example 10 were substantially repeated except that 0.858 g
of a soybean oil, 1.239 g of methanol and 10.2 mg of powdery zinc
oxide (ZnO) were used. The results of analysis made on the
recovered reaction solution showed that the yield of the methyl
ester was about 58% and that of glycerol was about 30%.
TABLE 1 Soybean Amount of Yield Yield oil Methanol Catalyst
catalyst Temperature Period (%) of (%) of Analysis by GPC (g) (g)
compound (mg) (.degree. C.) (min.) MES glycerol MES % MG % DC % TG
% Example 1 0.860 1.240 Sodium 5.8 300 10 99% 99% 98% 2% 0% 0%
carbonate Example 2 0.854 1.241 Calcium 5.0 300 10 97% 82% 98% 2%
0% 0% oxide Example 3 0.864 1.249 Calcium 5.9 300 10 98% 87% 99% 1%
0% 0% hydroxide Example 4 0.853 1.239 Magnesium 11.2 300 10 91% 73%
86% 7% 4% 3% oxide Example 5 0.861 1.243 Sodium 10.5 350 4 95% 90%
99% 1% 0% 0% carbonate Example 6 0.845 1.223 Calcium 0.085 300 10
98% 103% 96% 3% 2% 0% hydroxide Example 7 0.842 1.228 Calcium 0.084
300 10 97% 104% 96% 3% 1% 0% oxide Example 8 0.852 1.223 Calcium
0.085 300 10 98% 103% 96% 3% 1% 0% carbonate Example 9 0.744 1.084
Calcium 0.074 400 2 -- -- 95% 3% 2% 0% hydroxide Comparative 0.866
1.248 Sodium 10.0 250 10 87% 68% 78% 6% 6% 10% example 1 carbonate
In Table, MES means methyl ester, MG monoglyceride, DG diglyceride
and TG triglyceride.
* * * * *